1. Technical Field
The present invention relates to an optical image lens system. More particularly, the present invention relates to a compact optical image lens system applicable to electronic products and three-dimensional (3D) image applications thereof.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand of miniaturized optical lens systems is increasing. The sensor of a conventional photographing camera is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical lens systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical lens systems featuring better image quality.
A conventional compact optical lens system employed in a portable electronic product mainly adopts a structure of four-element lens such as the one disclosed in U.S. Pat. No. 7,869,142. Due to the popularity of mobile products with high-end specifications, such as smart phones and PDAs (Personal Digital Assistants), the requirements for high resolution and image quality of modern compact optical lens systems has been increasing significantly. However, the conventional four-element lens structure cannot satisfy these requirements of the compact optical lens system.
Although other conventional optical lens system with five-element lens structure such as the ones disclosed in U.S. Pat. No. 8,000,030 and U.S. Pat. No. 8,000,031 enhance image quality and resolving power, these optical designs still reside with unsolved problems. Since there are no three continuous lens elements closest to the object side with positive refractive power, it is not favorable for presenting its telephoto functionality in which the telephoto ratio is thereby limited. These optical designs are also hard to keep the lens system compact while achieving for the same telephoto ratio. Besides, these optical designs are not favorable for reducing the sensitivity of the lens system because its positive refractive power of these optical systems is not effectively distributed.